Plastics are used as common materials of hollow containers, such as containers with a lid and bottles, for their excellent molding properties and productivity. However, because plastic hollow containers involve various problems associated with waste disposal, hollow containers made of pulp are conceivable substitutes for plastic containers. Pulp-made hollow containers are not only easy to dispose of but economical because they can be manufactured from used paper.
Known techniques pertaining to pulp-made hollow containers include the technique disclosed in Japanese Patent Laid-Open No. 5-279998. The container disclosed has an angle of 45° or more at which the side walls rise and a depth of 15 mm or more. Because this container is produced by pressing a pulp layer deposited on a papermaking net with a pressing mold and then hot pressed in a metal mold, it is virtually impossible to make the side walls stand at an angle approximately 90° or more and to make the bottom deeper.
A bottle having an annular rib-like projection on its periphery is also known as another technique relating to pulp molded containers. Since the bottle is made by separately forming a pulp layer on each of a pair of splits and then closing the splits to join the two pulp layers, it unavoidably has seams at the joint. Such seams reduce the bottle strength and also impair the appearance.
Accordingly, an object of the present invention is to provide a molded article made mainly of pulp the side walls of which have a large angle to the ground and which has a large depth.
Another object of the present invention is to provide a molded article made mainly of pulp which involves no reduction in bottle strength has a satisfactory appearance, and has a depression or a projection of prescribed shape around the opening or the body thereof.